Evaluation of prosthetic venous valves, fabricated by electrospinning, for percutaneous treatment of chronic venous insufficiency.

Chronic venous insufficiency (CVI) remains a major health problem worldwide. Direct venous valve surgical repair and venous segment transplantation are clinical options; however, they are highly invasive procedures. The objectives of this study were to fabricate prosthetic venous valves (PVVs) by electrospinning, for percutaneous treatment of CVI, and evaluate their hydrodynamic characteristics in vitro at the same locations and under the same flow conditions. The PVVs consisted of polyurethane fiber scaffolds attached to a cobalt-chromium stent. PVVs with two different valve-leaflet configurations were compared: biomimetic PVV (bPVV) and open PVV (oPVV). A balloon catheter was used to implant the devices in a poly(vinyl chloride) tube and the column outlet was set at a height of 100 cm above the test valve to simulate the elevation of the heart above a distal vein valve while standing; 50 wt% glycerin solution was used as the test fluid. The devices were evaluated for antegrade flow, effect of ankle flexion, and stagnation zones around the valve leaflets. During sudden hydrostatic backpressure, little leakage and constant peripheral pressure were observed for the devices; under forward pulsatile pressure of 0-4 mmHg, to simulate the effect of breathing, the oPVV had a higher flow rate than the bPVV. With regard to the effect of ankle flexion, the oPVV was functionless. Moreover, the stagnation zone around the oPVV valve leaflets was larger than that around the bPVV valve leaflets. These results suggest that the bPVV would be clinically suitable for percutaneous treatment of CVI.

Development of nanofiber-covered stents using electrospinning: in vitro and acute phase in vivo experiments.

There are some technical difficulties in treating for a broad necked aneurysm and a higher incidence of recurrence. Because of these drawbacks, more innovative techniques for superior endovascular reconstructive treatment are required. We developed a novel covered stent employing electrospinning to deposit fine polyurethane (PU) fibers onto stents. An in vitro water leak test was designed and applied prior to animal testing to estimate the performance of covered stents and to determine the appropriate amount of PU fibers on a stent. Two tenths of a milligram of PU fibers proved to be sufficient to prevent water leakage. Then, the efficacy of the covered stents to that of bare stents was compared using 10 rabbits in which model aneurysms had been formed at the right common carotid artery by the elastase method. Angiographic evaluation on day 1 posttreatment (acute phase) revealed complete occlusion of the aneurysms and the patency of the parent arteries in animals treated with covered stents. At 10 days poststenting (subacute phase), the aneurysm neck was completely covered with neointimal layer as shown by scanning electron microscopic examination. The PU-covered stent holds promise as a device for treating cerebral aneurysms.